This invention relates to a production method of a weather strip for an automobile, which is installed on an opening edge of an automobile body to seal a gap between the automobile body and an open-close member positioned in opposition to the automobile body by means of an elastic contact with the open-close member.
A comparative structure of a weather strip is illustrated in FIG. 8. This weather strip 200 is installed on an opening edge of an automobile body to conduct an elastic contact with an open-close member such as a door positioned in opposition to the automobile body in order to seal a gap between the body and the open-close member.
As illustrated in the sectional view in FIG. 8, the weather strip 200 for an automobile mainly comprises an installation base member 1 which is installed to an opening edge of an automobile body, a hollow seal member 5 which is integrally molded with the installation base member 1 for conducting the elastic contact with the open-close member such as the door positioned in opposition to the automobile body, and a lip member 6.
The installation base member 1 is composed of a bottom wall portion 11 and side wall portions 12, 13 each of which extends from a corresponding end edge of the bottom wall portion 11, forming a groove portion 10 which roughly forms an U shape in section. Further, there is provided a holding lip 2 inside the groove portion 10, which functions as a holding member when installing the installation base member 1 on the opening edge of the automobile body.
The each member described above is made of rubber.
Further, a metal made insert 7 is embedded inside the installation base member 1 in order to provide the installation base member with rigidity.
In this structure, a steel plate forming the opening edge of the automobile body on which the installation base member 1 is installed is not uniform in thickness but the thickness of the steel plate varies depending on portions of the opening edge in general. Therefore, when producing the weather strip 200 for an automobile, the holding lip 2 is subjected to a manufacturing process to correspond with the thickness variation of the steel plate.
This production method is performed by a process illustrated in FIG. 7.
In this production method, the whole weather strip 200 is formed by an extrusion-molding (Extrusion-molding process 201) first.
Secondly, the holding lip 2 is processed to vary its shape in accordance with a portion in a longitudinal direction by pushing the holding lip 2 toward a side of the side wall portion 13 or grinding the holding lip 2, after inserting a manufacturing tool 8 in the groove portion 10 of the installation base member 1 which has been extrusion-molded (Holding lip manufacturing process 202).
Lastly, the whole weather strip 200 is vulcanized (Vulcanization process 203).
By processing the holding lip 2 to correspond its shape with the thickness variation of the metal plate forming the opening edge of the automobile body, it is possible to install the weather strip 200 properly.
Besides the above-mentioned weather strip 200 for an automobile, in recent years, for the purposes of weight saving and recycling, there have been produced weather strips which comprise installation base members embedding plastic-made inserts such as thermoplastic resin instead of the metal-made inserts 7.
FIG. 9 is a sectional view showing a weather strip 300 for an automobile embedding a plastic-made insert 4 in an installation base member 1.
In such weather strip, the plastic-made insert 4 is lighter than the metal made insert 7, but the plastic-made insert 4 is softened by heat. Therefore, the weather strip 300 embedding such plastic-made insert 4 may deform in a vulcanization process.
In order to prevent the deformation, as illustrated in the sectional view in FIG. 9, it is possible to improve rigidity by integrally extrusion-molding a lid member 3 connecting both end portions of side wall portions 12, 13 and covering an opening of a groove portion 10. Then the lid member 3 can be removed after completion of vulcanization process.
However, if the opening of the groove portion 10 is covered with the lid member 3 as illustrated in FIG. 9, it is impossible to insert the manufacturing tool 8 into the groove portion 10 of the installation base member 1 after the extrusion-molding for processing a holding lip 2 because the lid member 3 interferes. Therefore, the process of adjusting the holding lip 2 in accordance with the thickness of the metal plate cannot be performed.
For such reasons, it is difficult to produce a weather strip comprising a plastic-made insert instead of a metal made insert by adjusting with a thickness variation of a metal plate forming an opening edge of an automobile body.
The invention is aimed at solution of the above-mentioned problem providing a production method in which the holding lip can be processed in accordance with thickness of the metal plate forming the opening edge of an automobile body in producing the weather strip for an automobile embedding the plastic-made insert in the installation base member.